Yii2: Show and filter relational table in gridview

Question

I have two tables: people & categories

People

- id
- name
- ...

Categories

- id
- name
- description

And another table with the relation between both as one person can have multiple categories assigned:

PeopleCategoriesAssn

- peopleID
- categoryID

I can show the categories IDs in my gridview (views/people/index.php) with:

<?= GridView::widget([
    'dataProvider' => $dataProvider,
    'filterModel' => $searchModel,
    'columns' => [
        ...,
        [
            'label' => 'Category',
            'value' => function ($data) {
                $output = '';
                foreach($data->peopleCategoriesAssns as $request) {
                    $output .= $request->talentCategoryID.'<br>';
                }
                return $output;
            },
        ],
        ...

which uses this from models/People.php

public function getPeopleCategoriesAssns() 
{ 
    return $this->hasMany(PeopleCategoriesAssn::className(), ['peopleID' => 'id']); 
} 

How could I show the categories names instead of the categoies IDs within the gridview and also, what should i do at /models/PeopleSearch.php in order to allow search/filter on that field?

Thank you in advance,

Answer 1

To answer the first part you need to add another method to the People class:

public function getCategories() {
    return $this->hasMany( Categories::className(), [ 'id' => 'categoryID' ] )
                ->via('PeopleCategoriesAssn');
}

See: http://www.yiiframework.com/doc-2.0/yii-db-activerelationtrait.html#via()-detail

This will allow you to do:

foreach( $data->categories as $category) {
    $output .= $category->name.'<br>';
}

As for searching, I'm not sure, but adding public $categoryName property to the search class would be a good starting point.

Answer 2

There are two parts involved with your problem.

1. Showing the values

This is just a respecification of your GridView -column:

'columns'=>[
    //...
    [
        'attribute'=>'catNameSearch',
        'value'=>function ($model, $key, $index, $column) {
            $cats = $model->peopleCategoriesAssns;
            if (empty($cats)) {
                return null;
            } else {
                return implode(', ', ArrayHelper::getColumn($cats, 'name');
            }
        },
    ],
    //...
]

2. Searching cat names

Now to solve the problem of searching them it gets a little more complex. As you can see I set the attribute above to catNameSearch . You need to add this as a public var to your PeopleSearch -class and declare it as safe in a validator of the search-class.

class PeopleSearch extends \app\models\People
{

    public $catNameSearch;

    public function rules()
    {
        return [
            //...
            [['catNameSearch'], 'safe'],
            //...
        ];
    }
 }

In the search-method itself you add a sub-query to show only people assigned to the corresponding category. This could be done like so:

if (!empty($this->catNameSearch)) {
    $peopleIdsMatching = PeopleCategoriesAssn::find()
         ->select('peopleID')
         ->distinct(true)
         ->joinWidth('category')
         ->andWhere(['like', ['category.name'=>$this->catNameSearch]])
        ->column();

     $this->andWhere(['id'=>$peopleIdsMatching]);
}

Now only people with a relation to the given category will be shown. This could be further optimized with performing the comparison in an actual sub-query of the people-search and not doing a seperate query, but this should give you the basic idea!